Property- and position-based catheter probe target identification

ABSTRACT

Methods and systems for position determination of an intrabody probe, targets of an intrabody probe, and or actions to be performed using an intrabody probe are described. In some embodiments, an anatomy being navigated and/or mapped is described by a rule-based schema relating different anatomically identified structures to one another according to their ability to help identify and/or locate one another. Additionally, in some embodiments, data recorded from the intrabody probe is processed according to schema rules in order to provide anatomical identification of the anatomical region which the intrabody probe is sampling, optionally without performing detailed mapping, and/or prior to the availability of detailed mapping of anatomical geometry.

RELATED APPLICATIONS

This application is a National Phase of PCT Patent Application No.PCT/IB2018/053258 having International filing date of May 10, 2018,which claims the benefit of priority under 35 USC § 119(e) of U.S.Provisional Patent Application No. 62/504,339 filed on May 10, 2017.

PCT Patent Application No. PCT/IB2018/053258 is also related to U.S.Provisional Patent Application No. 62/362,146 filed on Jul. 14, 2016 andentitled “CHARACTERISTIC TRACK CATHETER NAVIGATION”; U.S. ProvisionalPatent Application No. 62/422,748 filed on Nov. 16, 2016 and entitled“ESTIMATORS FOR ABLATION EFFECTIVENESS”; and U.S. Provisional PatentApplication No. 62/422,767 filed on Nov. 16, 2016 and entitled“ESOPHAGUS POSITION DETECTION BY ELECTRICAL MAPPING”.

The contents of the above applications are all incorporated by referenceas if fully set forth herein in their entirety.

FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates to the fieldof navigation of body cavities by intra-body probes, and moreparticularly, to determination of intra-body probe position, for exampleduring navigation of body cavities.

Several medical procedures in cardiology and other medical fieldscomprise the use of intrabody probes such as catheter probes to reachtissue targeted for diagnosis and/or treatment while minimizingprocedure invasiveness. Early imaging-based techniques (such asfluoroscopy) for navigation of the catheter and monitoring of treatmentscontinue to be refined, and are now joined by techniques such aselectrical field-guided position sensing systems.

SUMMARY OF THE INVENTION

There is provided, in accordance with some embodiments of the presentdisclosure, a method of determining an anatomical identity of a firstintrabody region using an intrabody probe, the method comprising:receiving data indicating an operational context; receiving input datafrom the intrabody probe indicating one or more measured properties ofthe first intrabody region; selecting at least one rule for anatomicalidentification from an anatomical schema, wherein the at least one ruleis selected based on the operational context; and applying the at leastone rule to the input data, to determine anatomical identity of thefirst intrabody region.

In some embodiments, the method comprises: selecting a second at leastone rule for anatomical identification from the anatomical schema, basedon the current operational context; and applying the second at least onerule to identify a second intrabody region, based on a relationshipbetween the second intrabody region and the first intrabody regionexpressed by a rule of the anatomical schema, and the anatomicalidentity determined for the first intrabody region.

In some embodiments, the method comprises associating the anatomicalidentity determined for the first region to a geometrical representationof the first intrabody region.

In some embodiments, the method comprises displaying the anatomicalidentity determined for the first intrabody region together with adisplay of the geometrical representation of the first intrabody region.

In some embodiments, the method comprises guiding navigation of theintrabody probe to the first intrabody region, based on the anatomicalidentity determined for the first intrabody region.

In some embodiments, the method comprises using the intrabody probe toperform an action upon the first intrabody region, based on theanatomical identity determined for the first intrabody region.

In some embodiments, the input data does not include image data.

In some embodiments, the data indicating a current operational contextcomprise non-image data.

In some embodiments, the input data comprises electrical measurementsfrom the intrabody region.

In some embodiments, the electrical measurements comprise voltagemeasurements.

In some embodiments, the electrical measurements comprise impedancemeasurements.

There is provided, in accordance with some embodiments of the presentdisclosure, a method of generating an estimator of an anatomicalidentity of an intrabody region based on input data collected from anintrabody probe, comprising: obtaining a plurality of indications fromat least one skilled operator of the intrabody probe, wherein theindications are of an anatomical identity of intrabody regionscorresponding to different intrabody positions of the intrabody probewhile the input data was collected; and processing the input datatogether with the plurality of indications to generate an estimatorconfigured to identify the intrabody region, based on new input datacollected from an intrabody probe.

In some embodiments, the input data comprises electrical measurementsfrom the intrabody region.

In some embodiments, the processing comprises processing to generate aplurality of the estimators, each for identifying a correspondingintrabody region, based on the input data and the plurality ofindications.

In some embodiments, the processing comprises application of a machinelearning method.

There is provided, in accordance with some embodiments of the presentdisclosure, a method of crossing an interatrial septum, comprising:recording the position of an intrabody probe at multiple locationsadjoining the interatrial septum while the intrabody probe measures dataindicating a tissue property of the interatrial septum at each of themultiple locations; and identifying the thinnest zone of the interatrialseptum, based on electrical measurements in the right atrium; andproviding the crossing location across which the intrabody probe is tobe moved, based on the identification of the thinnest zone.

In some embodiments, the measured indicating data comprise an electricalfield parameter affected by the indicated tissue property.

In some embodiments, the intrabody probe comprises a needle, and thedata indicating the tissue property is electrically sensed using theneedle.

In some embodiments, the method comprises sensing a change in anelectrical signal as the needle extends from a sheath to cross thecrossing location, and displaying tenting movement of a simulateddisplay of the interatrial septum in correspondence with the sensedchange in the electrical signal.

In some embodiments, the moving the intrabody probe across the crossinglocation comprises ablating at the crossing location using the probe toweaken tissue at the crossing location.

In some embodiments, the method comprises using the same intrabody probeto perform another ablation in a heart chamber entered after crossingthe crossing location.

There is provided, in accordance with some embodiments of the presentdisclosure, a method of verifying the placement of a cryoballoon,comprising: monitoring output from a sensing electrode of an intrabodyprobe as the electrode is inserted into an opening of a pulmonary vein;detecting a predetermined change in the output of the sensing electrode;and providing an indication of occlusion of the opening, based on thedetection of the predetermined change.

In some embodiments, the occlusion of the opening is sufficient to blockblood flow through the opening.

In some embodiments, the indication comprises an indication that theintrabody probe is in a position suitable for ablation.

In some embodiments, the suitable position comprises the cryoballoonbeing in contact with tissue near the vein opening around anuninterrupted perimeter.

There is provided, in accordance with some embodiments of the presentdisclosure, an apparatus for determining an anatomical identity of anintrabody region, the apparatus comprising: an interface configured toreceive from a user of the apparatus data indicating an operationalcontext; an intrabody probe input for receiving input data from theintrabody probe indicating one or more measured properties of theintrabody region; a memory storing a plurality of rules for determiningthe identity of the intrabody region, each rule being associated with arespective operational context; and a processor configured to: select atleast one rule from the memory based on the operational context receivedthrough the interface; and determine the anatomical identity of theintrabody region by applying the at least one rule to the input data.

In some embodiments, the processor is configured to associate thedetermined anatomical identity to a geometrical representation of theintrabody region.

In some embodiments, the processor is also configured to provide fordisplay the anatomical identity together with the geometricalrepresentation of the intrabody region.

There is provided, in accordance with some embodiments of the presentdisclosure, a method of determining an action to perform within anintrabody region using an intrabody probe, the method comprising:receiving data indicating an operational context, as well as a targetselection indicating an anatomical portion of the intrabody region uponwhich an action is to be performed; receiving input data from theintrabody probe indicating one or more measured properties of theintrabody region; selecting at least one rule for determining the actionfrom a procedure schema, wherein the at least one rule is selected basedon the current operational context and the target selection; andapplying the at least one rule to the input data, to determine theaction.

In some embodiments, the determined action comprises guiding navigationof the intrabody probe to the anatomical portion indicated by the targetselection.

Unless otherwise defined, all technical and/or scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which the invention pertains. Although methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of embodiments of the invention, exemplarymethods and/or materials are described below. In case of conflict, thepatent specification, including definitions, will control. In addition,the materials, methods, and examples are illustrative only and are notintended to be necessarily limiting.

As will be appreciated by one skilled in the art, aspects of the presentinvention may be embodied as a system, method or computer programproduct. Accordingly, aspects of the present invention may take the formof an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, some embodiments of the present invention may take the formof a computer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.Implementation of the method and/or system of some embodiments of theinvention can involve performing and/or completing selected tasksmanually, automatically, or a combination thereof. Moreover, accordingto actual instrumentation and equipment of some embodiments of themethod and/or system of the invention, several selected tasks could beimplemented by hardware, by software or by firmware and/or by acombination thereof, e.g., using an operating system.

For example, hardware for performing selected tasks according to someembodiments of the invention could be implemented as a chip or acircuit. As software, selected tasks according to some embodiments ofthe invention could be implemented as a plurality of softwareinstructions being executed by a computer using any suitable operatingsystem. In an exemplary embodiment of the invention, one or more tasksaccording to some exemplary embodiments of method and/or system asdescribed herein are performed by a data processor, such as a computingplatform for executing a plurality of instructions. Optionally, the dataprocessor includes a volatile memory for storing instructions and/ordata and/or a non-volatile storage, for example, a magnetic hard-diskand/or removable media, for storing instructions and/or data.Optionally, a network connection is provided as well. A display and/or auser input device such as a keyboard or mouse are optionally provided aswell.

Any combination of one or more computer readable medium(s) may beutilized for some embodiments of the invention. The computer readablemedium may be a computer readable signal medium or a computer readablestorage medium. A computer readable storage medium may be, for example,but not limited to, an electronic, magnetic, optical, electromagnetic,infrared, or semiconductor system, apparatus, or device, or any suitablecombination of the foregoing. More specific examples (a non-exhaustivelist) of the computer readable storage medium would include thefollowing: an electrical connection having one or more wires, a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), an optical fiber, a portable compact disc read-onlymemory (CD-ROM), an optical storage device, a magnetic storage device,or any suitable combination of the foregoing. In the context of thisdocument, a computer readable storage medium may be any tangible mediumthat can contain, or store a program for use by or in connection with aninstruction execution system, apparatus, or device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable medium and/or data usedthereby may be transmitted using any appropriate medium, including butnot limited to wireless, wireline, optical fiber cable, RF, etc., or anysuitable combination of the foregoing.

Computer program code for carrying out operations for some embodimentsof the present invention may be written in any combination of one ormore programming languages, including an object oriented programminglanguage such as Java, Smalltalk, C++ or the like and conventionalprocedural programming languages, such as the “C” programming languageor similar programming languages. The program code may execute entirelyon the user's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer (for example, through the Internet using an Internet ServiceProvider).

Some embodiments of the present invention may be described below withreference to flowchart illustrations and/or block diagrams of methods,apparatus (systems) and computer program products according toembodiments of the invention. It will be understood that each block ofthe flowchart illustrations and/or block diagrams, and combinations ofblocks in the flowchart illustrations and/or block diagrams, can beimplemented by computer program instructions. These computer programinstructions may be provided to a processor of a general purposecomputer, special purpose computer, or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which execute via the processor of the computer or other programmabledata processing apparatus, create means for implementing thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Some embodiments of the invention are herein described, by way ofexample only, with reference to the accompanying drawings. With specificreference now to the drawings in detail, it is stressed that theparticulars shown are by way of example, and for purposes ofillustrative discussion of embodiments of the invention. In this regard,the description taken with the drawings makes apparent to those skilledin the art how embodiments of the invention may be practiced.

In the drawings:

FIG. 1A schematically represents a method of automatic anatomicalidentification of an intrabody target, and optionally automaticsuggestion of a selected action on that target, according to someembodiments of the present disclosure;

FIG. 1B is a schematic flowchart of the use the method of FIG. 1A withinthe context of a procedure, according to some embodiments of the presentdisclosure.

FIG. 1C schematically represents a method of automatic anatomicalidentification of an intrabody region, according to some embodiments ofthe present disclosure;

FIG. 1D schematically represents a method of automatic suggestion of aselected action on a target, according to some embodiments of thepresent disclosure;

FIG. 2A schematically illustrates a system for use in performing themethods of FIGS. 1A-1B, including a schematic representation of apatient body, according to some embodiments of the present disclosure;

FIG. 2B schematically represents inputs and operations of an estimatorservices module, according to some embodiments of the presentdisclosure;

FIG. 3A schematically represents selected anatomical relationshipsencoded by an anatomical schema, according to some embodiments of thepresent disclosure;

FIG. 3B illustrates some of the left atrium features mentioned in FIG.3A in an “unwrapped” view of the left atrium, according to someembodiments of the present disclosure;

FIG. 3C is a schematic flowchart of the use of machine learning toestablish at least some aspects of an anatomical schema, according tosome embodiments of the present disclosure;

FIGS. 4A-4C schematically represent crossing by a catheter probe from aright atrium across an interatrial septum to a left atrium via a fossaovalis, according to some embodiments of the present disclosure;

FIG. 5 is a schematic flowchart describing a method of locating a fossaovalis, according to some embodiments of the present disclosure;

FIG. 6 is a schematic flowchart describing a method of crossing a fossaovalis using an electrically monitored needle, according to someembodiments of the present disclosure;

FIGS. 7A-7B schematically represent stages in cryoablation includinginsertion of a lasso catheter probe into a pulmonary vein of a leftatrium, and conversion of blood flow into blocked flow as a cryoballoonis pressed firmly up against the ostium leading into pulmonary vein,according to some embodiments of the present disclosure;

FIG. 8 is a schematic flowchart describing a method for electricalmonitoring of the flow blockage shown in FIGS. 7A-7B, according to someembodiments of the present disclosure;

FIGS. 9A-9D schematically represent test results of the method of FIG. 8, according to some embodiments of the present disclosure;

FIGS. 10A-10B respectively represent visual results of cryoablation invitro on a muscle tissue preparation (FIG. 10A), and dielectricassessment of the same results (FIG. 10B) which reveals a potential gapin the apparently well-ablated region, according to some embodiments ofthe present disclosure; and

FIG. 11 is a schematic flowchart describing a method forsingle-electrode transseptal penetration from the right to the leftatria, followed by ablation within the left atrium, according to someembodiments of the present disclosure.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

The present invention, in some embodiments thereof, relates to the fieldof navigation of body cavities by intra-body probes, and moreparticularly, to determination of intra-body probe position, for exampleduring navigation of body cavities.

Overview

A broad aspect of some embodiments of the present invention relates touse of catheter probe measurements to establish anatomical identity ofintrabody regions, particularly intrabody regions in the vicinity of theprobe.

Methods for determining the anatomical geometry of intrabody regionsnavigated by catheters have been described based on many differenttechniques; for example, CT imaging, X-ray angiographic imaging, MRIimaging, ultrasound imaging, electrical field-guided probe navigation,and magnetic field-guided probe navigation.

Some such methods build up a reconstruction of anatomical geometry basedat least in part on data acquired on the fly during a catheterizationprocedure. For example, methods using electrical field-guided probenavigation may use electrically recorded data to build up an anatomicalmodel which gradually increases in coverage, resolution, and/or accuracyas a procedure progresses. Accordingly, an operator may be presentedwith a need to perform procedure operations based on incompletegeometrical information. Moreover, and potentially even in situationswhere anatomical geometry is well-represented, an operator (particularlyan inexperienced operator) may occasionally become confused in making ananatomical identification based on anatomical geometry informationalone.

Misidentification of anatomical position, even if rare, potentiallyleads to serious complications. For example, trans-septal passage of anintracardiac catheter is a complicated intervention, which even after200 cases of training has been associated with a risk of serious adverseevents in the range of about 2%. One type of adverse event comprisespenetration of the wrong part of the heart wall. Potentially,improvements in making the link between anatomical geometry andidentification of that geometry as being of a particular (e.g., named)anatomical structure would help reduce such rates of complication.

Herein, a distinction is drawn between anatomical geometry andanatomical identity. Anatomical geometry comprises shapes of anatomy,and relationships among those shapes in the definition of largerstructures. As examples of anatomical geometry: a heart chamber has a(dynamically changing) roughly globular shape, from which one or moretubular blood vessels extend; the heart chamber also is in fluidcommunication with another roughly globular-shaped heart chamber.Anatomical identity comprises assigning to an anatomical position anidentity as belonging to a particular anatomically defined structure,such as a right atrium, pulmonary vein, or even more particularly, forexample, as an interatrial septum, foramen ovale, ostium of a pulmonaryvein, atrial appendage, and/or another anatomical structure. Theidentified position may be a position defined within a modeledanatomical geometry; for example, the position of a shape appearing inthe model or any portion thereof. In some embodiments, the identifiedposition may be a point-like position.

Anatomical identity of a position can generally be deduced from asufficiently complete representation of anatomical geometry (e.g., byconsideration of shapes at the position itself and/or the relationshipof the position to shapes in other, e.g., adjacent, positions). But thetwo are distinct; for example, it can be understood that a blood vesselmay be accidentally misidentified even by an operator viewing a detailedmodel. Working from a partial model of anatomical geometry, anatomicalidentity may be still more ambiguous. Other information, for example asdescribed herein, may augment and/or replace the use of anatomicalgeometry in establishing anatomical identity.

Unless otherwise indicated, anatomical identity is generally understoodto refer to macroscopic anatomical structures (e.g., of a region beingnavigated by a catheter probe). These macroscopic structures optionallycorrespond to named anatomical parts. However, in some embodiments,anatomical identity is optionally made at least in part according todistinctions other than those of the standard anatomical nomenclature,which can be made from available data. For example, different anatomicalidentities may be assigned to regions with different tissue wallthicknesses, or other structural and/or positional differences which canbe detected (e.g., by the use of dielectric measurements), but do notnecessarily correlate with distinctions made by standard anatomicalnomenclature.

An aspect of some embodiments of the present invention relates toautomatic anatomical identification of an intrabody region based oncombined inputs from a plurality of measurement sources.

In some embodiments, the plurality of measurement sources comprises atleast one source giving positional information, and at least one sourcegiving measurements of one or more properties which vary at differentpositions (e.g., electrical impedance at a position, and/or S-matrixdescribing an electrode array at the position). For example, a firstsource may give partial positional information, e.g., how far advanced acatheter is into a body, and/or what route a catheter used to reach itscurrent location. Measurements from the second source may be used todetermine position more specifically, with constraints applied to thedetermination based on the partial positional information of the firstsource.

An aspect of some embodiments of the present invention relates to theuse of supervised machine learning to create one or more data structuresuseful in automatic anatomical identification of an intrabody region. Arelated aspect of some embodiments of the present invention relates tothe provision of automatic indications of procedure actions to beperformed in those regions.

In some embodiments, the one or more data structures include informationdescribing anatomical variations (e.g., variation in numbers, sizes,local morphology, and/or relative positions of anatomical structures)which may be encountered during a procedure. Optionally, identificationof one or more particular anatomical variations is further linked toautomatic indication (e.g., recommendation) of procedure changes topotentially adapt procedure actions to the specific exigencies of ananatomical variation.

Some practitioners especially skilled in a procedure can identifyintrabody regions, appropriate times, and/or alternatives for procedureactions with a high probability of success compared to peers. It wouldbe of potential benefit to embed aspects of this skill in an automaticadvisory system for use by less-skilled practitioners. In someprocedures, for example, intervention procedures performed over catheterby indirect visualization, nearly all of the inputs (and many of theoutputs) generated during a procedure are recorded in a digital form,which may capture substantially all the information which was availableto a practitioner during performance of the procedure. This conditionprovides an opportunity for expert skill capture to an automatic system,based on supervised learning.

In some embodiments, the digital records of a plurality of catheterprocedures are used, together with supervised machine learning, toproduce an automatic advisory system linking different situationalspecifics to different suggested actions. For example, all datapresented to a skilled practitioner before some procedure action (and/orduring the procedure action) are treated as training inputs, whilesubsequent commanded movements and other actions are treated as feedbackinput which suggests what is to be done in response to the traininginputs, when to do it, and/or to what degree to do it.

Optionally, in some embodiments, a skilled practitioner providesadditional indications (narration, for example), describing features oftheir judgments and/or intentions which may not be inherently visible intheir recorded actions. Optionally, procedure records (with or withoutsupplementary annotations from a practitioner) are subjected to furthermarkup before use in machine learning, for example to divide and/orlabel epochs within the procedure record, and/or to change the weightingof different aspects of recorded information (e.g., if the skilledpractitioner has highlighted some feature during the procedure asimportant to decision making, and/or if there is some aspect ofprocedure action timing, extent and/or degree which should be a subjectof particular focus for the machine learning). Optionally,post-procedure data (for example, procedure outcome results) are alsoprovided as part of the machine learning input.

In some embodiments, machine learning is used to advise a procedurepractitioner on the locations of heart structures. For example, inintervention to correct a defective heart valve, the atrial ventricularring to which the mitral and the tricuspid valves are attached is asignificant target. In some embodiments, a locatable intrabody probe(for example, a catheter probe) has at least one electrode. An ACcurrent is injected from each electrode, optionally at a respectivefrequency, or otherwise distinguished, to allow separate identificationof the electrodes used. The corresponding voltages generated on the sameand/or other electrodes are recorded and processed by a Processing Unit(PU). These data can serve as input examples used within a learning dataset (training data). Optionally, an expert practitioner providesfeedback on the input examples by identifying signal recorded at certainpositions as corresponding to a certain type of intra-body region,including target and non-target intrabody region; the latter being, anintrabody region excluded from being the subject of a certain procedureaction. This identification can be implicit, for example, by actualactions performed or explicit, for example by tagging the recordedinformation. An implicit identification by actions may include, forexample, identifying the fossa ovalis in a transseptal penetration, asthe part selected for penetration by the skilled physician. Additionallyor alternatively, the expert practitioner explicitly tags regions basedon their own judgments.

In some embodiments, machine learning for this example uses input datain the matrices of the S₁₁, S₁₂ . . . S_(ij) of the electrodes indifferent frequencies as well as the location of the probe relative to aknown fiducial mark, or relative to an already identified region. Anelement S_(ij) of an S matrix is a number, optionally a complex number,describing a ratio between an electrical field of a given frequencygoing through antenna i into the surroundings and an electrical field ofthe same frequency going at the same time through antenna j from thesurroundings, when each antenna transmits an electrical field of adistinct frequency, e.g., in the radio frequency range of theelectromagnetic spectrum. Optionally, the input data is provided formachine learning after normalization to correct for inter-patientvariability. Expert actions and/or expert-provided observations providethe supervisory training feedback that relates the input data toparticular cases, and serves as a basis for machine learning ofassociation between input data and corresponding expert evaluations.After the machine learning result is validated as producing correctevaluations and/or action recommendations in response to data on partsof which the machine was trained, the learning result may be used toevaluate and/or recommend actions in response to new input.

An aspect of some embodiments of the present invention relates toproviding of procedure guidance based on automatic anatomicalidentifications within an intrabody region.

In some embodiments, a procedure being guided comprises cryoablation. Insome embodiments, a cryoballoon is used to ablate a closed line oftissue, for example, surrounding an entrance of a pulmonary vein to theleft atrium. In some such embodiments, it is a potential advantage tohave an indication of when the cryoballoon closes off flow through thepulmonary vein, since such blockage of flow potentially indicates thatfully circumferential contact has been made by the balloon, so that agap-free ablation line can be formed.

In some embodiments, procedure guidance includes detection (andindication to a user) of changes in sensed voltage by one or moreelectrodes located within a pulmonary vein as a cryoballoon configuredfor use in cryoablation closes off flow through the pulmonary vein.

Optionally, automatic procedure guidance is developed using techniquesof machine learning. In some embodiments, experts indicate during aprocedure, or during analysis of a replay of a procedure, when flow isblocked; and the machine learns relations between such indications andelectrical potential readings. Results of the training may then be usedto procedure guidance by following in real time changes in electricalpotential detected by electrodes during a similar procedure carried outby a novice, and indicating when full blockage is achieved. In someembodiments, the system may be trained to identify actions to be takenonce the flow blockage is achieved, and recommend these actions to thenovice.

In some embodiments, a procedure being guided comprises penetrating theinteratrial wall by an ablation catheter. In some embodiments, anelectrode probe is passed over the interatrial wall while makingdielectric measurements. Thinner walls are observed to have differentdielectric properties than thicker walls. Optionally, position ofthinning (or actual holes) near the center of the interatrial wall aretreated as representing a target region across which an ablation probeis to penetrate the interatrial wall.

In some embodiments, a procedure to be guided comprises determining alocation of a valve plane (e.g., in preparation for valvular treatment),and/or determining a location of an opening into the coronary sinus(e.g., in preparation for cannulation of the coronary sinus).

Optionally, automatic procedure guidance is developed using techniquesof machine learning. In a learning stage, in some embodiments, an expertmarks when a catheter is at a target position (e.g., the valve plane orthe opening in the coronary sinus). The machine is trained todistinguish between readings of the electrodes at the target positionand readings of the electrodes off the target positions. Then, inanother procedure, the results of the training may be used to identifywhen the catheter is at the target position based on readings receivedfrom electrodes on the catheter.

For purposes of description, principles of the invention are describedherein with respect to detailed embodiments relating to mapping of thecardiovascular system (or portions thereof) and/or navigation of anintrabody probe (e.g., a catheter probe) within a portion of acardiovascular system. In some embodiments, the mapping and/ornavigation is performed in the context of a cardiac intervention, forexample: cardiac electrophysiological treatment, cardiac vasculartreatment, and/or cardiac structural heart disease treatment (forexample valvular treatments). It should be understood that in someembodiments, principles of the invention are applied, changed asnecessary as may be understood based on the provided examples, toanother medical intervention; for example: surgery, colonoscopy, biopsy,oncology surgery, orthopedic disk surgery, and/or plastic surgery.

Herein, a “map” (for example, as the term is used in relation to the actof “mapping”) should be understood to be a machine readable datastructure which describes a correspondence between values of ameasurable position-dependent parameter, and the spatial positions atwhich those values are found by measurement. Using a map, knowledge thata certain parameter value is measured at a current (but potentiallyunknown) position can be used to help identify what the position is. Theterm should be understood to encompass maps instantiated, for example,as images, data tables, coordinate arrays, and/or mathematicalfunctions. In some embodiments, a map also expresses spatialrelationships among different positions, for example, adjacency,direction, and/or relative distance. An image, for example, is a mapwhich indicates relationships of each of these sorts.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not necessarily limited in itsapplication to the details of construction and the arrangement of thecomponents and/or methods set forth in the following description and/orillustrated in the drawings. The invention is capable of otherembodiments or of being practiced or carried out in various ways.

Method of Targeting and/or Action Selection by Anatomical Identification

Reference is now made to FIG. 1A, which schematically represents amethod of automatic anatomical identification of a targeted intrabodyregion, and optionally automatic suggestion of a selected action on thattarget, according to some embodiments of the present disclosure.Reference is also made to FIG. 1C, which schematically represents amethod of automatic anatomical identification of an intrabody region.Further reference is made to FIG. 1D, which schematically represents amethod of automatic suggestion of a selected action on a target,according to some embodiments of the present disclosure.

At block 130, in some embodiments, the flowchart begins with selectionof a target of a catheter operation. Inputs to block 130, in someembodiments, include operational context 210, measurement data 206, andanatomical schema 204A. These inputs to block 130 are also discussed inrelation to other figures herein; in particular FIGS. 1B, 2A-2B, and3A-3B. The output of block 130, in some embodiments, is a targetselection 212A; wherein the target selection 212A selects from amongtargets defined in the anatomical schema 204A using the measurement data206 and the operational context 210. The implementation of the selectingis largely governed by features of the data structure comprisinganatomical schema 204A, which describe how operational context 210 andmeasurement data 206 are to be used, as now described in the followingbrief overviews.

Operational Contexts

In overview, operational context 210 comprises elements (or dataindicative thereof) that may serve as background against whichmeasurement data (e.g., measurement data measured using an intrabodyprobe) are interpreted. Elements of operational context 210 optionallyinclude, for example:

-   -   system settings,    -   positioning of an intrabody probe (e.g., positioning in a        generally specified anatomical location, for example “in a left        atrium”, “in a right atrium”, “in an aorta”, “in a vena cava”,        “in the transverse colon”, “in a bladder”, or another anatomical        location which is known from operational context data, but not        as specific as the determination which is to be made using        measurement data 206),    -   state of an intrabody probe (e.g., operating state of an        ablation probe, expansion state of an expandable and/or        collapsible probe, and/or actuation state of a mechanically        operated probe),    -   status of a monitoring and/or control system supporting use of        the intrabody probe, and/or    -   the state of the patient undergoing the procedure.

For example, operational context 210 corresponds, in some embodiments,to state of components in a system such as the one described in relationto FIG. 2A, herein. More particularly, operational context 210 mayinclude data describing:

-   -   What procedure (e.g., a cardiac intervention procedure, for        example a procedure to treat atrial fibrillation by ablation) is        being performed,    -   Where are (in general) elements of the catheter probe system and        patient anatomy in relation to each other (for example “in the        left atrium”, “adjacent to the esophagus”, or another a phrase,        label, or categorization that indicates what parts of the        patient anatomy are in the vicinity of the probe),    -   In what state those elements are (e.g., operating state,        expansion state, and/or actuation state), and/or    -   What phase the procedure has reached.

In some embodiments, a system configured to carry out the method of FIG.1A tracks operational context 210 continually during a procedure.Tracking may be based on progress through a procedure schema 204B, forexample. In an example of such an embodiment, a system may set theoperational context 210 to comprise readiness to perform a transseptalcrossing upon detection of entry of the catheter into the vicinity(e.g., the lumen) of a right atrium.

Optionally, operational context 210 is set, at least in part, byexplicit indications from a system operator (e.g., a physician). Forexample, when the operator is ready to begin a transseptal penetration,the operator optionally issues a command to the system to enter atransseptal penetration mode, which sets the new operational context 210accordingly.

Measurement Data

In overview, measurement data 206 comprises available data which relatesto the procedure underway, and is used to characterize measurementlocations more specifically than the more general positioncharacterization which may be performed using the operational contextdata in absence of measurement data.

In some embodiments, measurement data 206 relates to tracked positions(for example, electrically, magnetically and/or ultrasonically trackedpositions) of a catheter probe, and/or measurements made using sensorsand/or electrodes carried by the probe. The sensors may include, forexample, force sensors and/or temperature sensors.

Electrical measurements may comprise, for example, voltage measurementsin response to currents introduced through the same probe electrodesand/or different electrodes, such as other internally introducedelectrodes and/or body surface electrodes. Optionally, electricalmeasurements comprise measurements of endogenous electrical activity oftissue near the catheter probe. Optionally, measurement data 206comprise data related to measurements of tissue response (e.g., thermaland/or electrical response) during treatment activation, when thetreatment activation includes, for example, activation of heating,cooling, injecting, irradiating, or otherwise therapeuticallyinteracting with nearby tissue. Optionally or alternatively, measurementdata 206 comprise data related to use of probing energies, such asirradiation, touching, or otherwise interacting with nearby tissue toprobe the nearby tissue.

In some embodiments, measurement data 206 comprise any other dataacquired and/or entered coordinate with operations of the procedure,including patient data (e.g., patient medical history, and/or vitalstatistics), patient monitoring data (e.g. heart rate, temperature,and/or respiratory rate), and/or previously or concurrently acquiredimaging data (CT, MRI, nuclear, and/or X-ray images, for example).

In some embodiments, measurement data is of a location of a probe. Thelocation may be recorded as absolute position and/or relative position.Optionally, location is recorded with respect to any suitable number ofdimensions. For example spatial dimensions of a three-axis coordinatesystem may be recorded. Optionally, spatial dimensions are encodedindirectly, e.g., as position along a voltage and/or impedance gradient.Any number of gradients may be used, for example, gradients generated atdifferent frequencies between a multiplicity of electrodes.Additionally/alternatively, time may be introduced as a dimension:linearly (elapsed time, for example), or cyclically (heartbeat phaseand/or respiratory phase, for example). Optionally, location is recordedby use of one or more measurement values acting as a “tag” or signatureof the location, for example, a set of impedance measurements.Optionally, other properties which may vary as a function of tissueenvironment are used; for example, any of the properties listed in thenext paragraph.

In some embodiments, recorded data is of local tissue properties; forexample: tissue thickness, molecular structure, IR reflectance, HoYaglaser reflection, endocardial and/or other electrical activity, pH,and/or ion concentration. Optionally electrical measurements related toexogenously created electrical navigation fields, local electricalimpedance, and/or local electrical reactance are treated as “localtissue properties”.

In some embodiments, recorded data indicates a tissue change in somemeasured parameter such as impedance and/or temperature. For example,change of the measured parameter may be as a function of: probepressure, heating, cooling, time per se, heartbeat phase, respiratorycycle, heart rate, defibrillation, and/or delivery of energy (which maybe ablation energy or another kind of delivered energy, for example totemporarily inactivate tissue). Optionally, the change is monitoredelectrically from a probe electrode, for example as the change affectsmeasurements of local impedance properties at one or more frequencies.Optionally, the monitored changing tissue property is directly relatedto the changed variable (for example, property of temperature ismonitored for heating/cooling).

Anatomical Schema

In overview, an anatomical schema 204A comprises a data structure orcollection of data structures defining rules. The rules relate aplurality of anatomical identities to one another (e.g., so that knowingthe anatomical identity of a first structure gives information, underthe rules, about what other anatomical structures are nearby that firststructure), and/or relate characteristics of measurement data 206 toparticular anatomical identities, at least within the operationalcontext (which may include, for example, an anatomical location and/or aprocedure phase) where the rule is relevant. Anatomical location may bea kind of location, described in reference to known landmarks (i.e.,known anatomical name and/or function). Optionally, an anatomical schema204A (or rule thereof) is defined for a particular operational context210 and/or as a function of operational context 210. A schematicrepresentation of an anatomical schema is described, for example, inrelation to FIG. 3A.

Herein, the term “rule” is used to describe any function, equation,table, model, machine learning output, or other expression which can beevaluated together with some input to produce a result. Examples ofresults include a number, truth value, a selection from a range ofoptions, a deductive conclusion, an inductive conclusion, and/or astatistical likelihood. Moreover, to be explicit: although certain typesof machine learning results are sometimes described as expressinginput/output associations without embodying distinct rules, herein sucha machine learning result may nevertheless be considered, in and ofitself, to embody at least a rule: that is, the rule of the expressedassociation that the machine learning result itself embodies.

As a partial example, again in the context of a procedure comprisingtransseptal penetration:

-   -   an “interatrial septum” is optionally defined in an anatomical        schema as comprising:        -   a “fossa ovalis”        -   wherein the fossa ovalis surrounded by regions (e.g.,            tracked positions in contact with wall tissue) which are            “not fossa ovalis”; and    -   wherein a rule distinguishing between the “fossa ovalis” and        “not fossa ovalis” operates on the basis of:        -   impedance measurement differences that correlate with wall            thickness (the fossa ovalis being found over a thinner            portion of the wall), and        -   optionally also on the basis of where the thinning is            located (i.e., in a central region of the interatrial            septum).

While the above description is presented in natural language for thesake of description, it should be understood that in some embodiments, arepresentation of an anatomical schema 204A for use in automaticprocessing is encoded in a suitable machine-readable format. Encodingoptionally uses, for example, XML (e.g. according to a purpose-designedXML schema), JSON or another computer language-derived data structuredescription, a numerically encoded (“binary”) format, weights for aneural network, another format suitable for encoding machine-learningderived algorithms, or in any other suitable format.

Relationships among regions of different anatomical identity which maybe expressed by defined rules (explicitly by coding and/or implicitly bymachine learning) in an anatomical schema 204A may include, for example,any one or more of the following, and/or their opposites as applicable:

-   -   Containing, being contained, comprising, or another relationship        of “composition”;    -   Adjacency, overlap, relative orientation, opposition (positions        opposite one another within a lumen), relative distance,        relative size or another relationship of spatial position and/or        extent;    -   Co-occurrence, mutual exclusivity, and/or likelihood of either;        and/or    -   Property correlations and/or relative values (e.g., co-variation        and/or consistent relative magnitudes of lumen size, wall        thickness, reactivity to stimulation, and/or susceptibility to        edema).

In some embodiments, an anatomical schema 204A includes alternativerules which allow the anatomical schema 204A to encompass certain typesof anatomical variability in a population. For example, in a normalpopulation, potentially 75% of the population will have a fossa ovalis(a depression in the right atrium of the heart, at the level of the wallbetween right and left atrium, which is the remnant of a thin fibroussheet that covered the foramen ovale during fetal development), and 25%of subjects will have a PFO (patent foramen ovale; that is, a fullopening in the interatrial septum dividing the right and left atria,instead of a mere reduction in wall thickness). An anatomical schema mayinclude rules to identify both characteristics of fossa ovalis and PFO.Other well-known variations in cardiac anatomy include but are notlimited to:

-   -   Unusual persistence (and/or size) of the Eustachian valve which        is normally only functional in fetal circulation,    -   Numbers of pulmonary veins leading to the left atrium other than        four (three, for example), and    -   A relatively pronounced ridge between the pulmonary veins and        the left atrial appendage (sometimes called a “warfarin ridge”        for its resemblance in some diagnostic results to a thrombus,        which may lead incorrectly to treatment with clot-thinning        drugs).

It is noted that the rules of an anatomical schema 204A do notnecessarily operate on the basis of precise descriptions of anatomicalgeometry (e.g., do not necessarily require reconstructions of tissuesurfaces). They may do so, in some embodiments. In other embodiments,the rules of an anatomical schema 204A definitely do not operate on thebasis of reconstructed tissue surfaces. Optionally, the rules operate onnon-image data, and optionally not on image data.

Herein, image data are considered to be data arranged in a datastructure that describes the value of a parameter at a multiplicity ofphysical spatial positions, according to a scheme that gives eachdescribed physical spatial position a definite and internally consistentdistance and direction from the other described positions. Non-imagedata used in an anatomical schema optionally represent positionsindefinitely—for example by the label of a general anatomical location,probabilistically (e.g., a range of likely relative distances), and/oraccording to threshold-defined ranges of distances. Optionally,non-image data represent positions according to parameter metrics whichdo not make use of physical position. As an example of non-image data:in some embodiments, anatomical schema 204A includes distributions ofanatomical geometries, for example, data pertaining to the frequency atwhich certain distances between two anatomical landmarks may appear. Inanother example, anatomical schema 204A specifies locations by labels:for example, labels corresponding to phrase definitions like “in theleft atrium”, “adjacent to the esophagus”. In a further example,anatomical schema 204A specifies categories which group anatomicallocations (assigns them “logical labels”), but do not provide them witha definite spatial ordering.

Even if precise position data is available (for example, based onposition tracking of a probe), use of comparison rules established by ananatomical schema 204A optionally ignores some or all of this precision.For example, it may not be relevant to a rule to know just how close tothe center of the interatrial septum a candidate position for a fossaovalis is, so long as, for example, it can be determined that there area substantial number of distinguishable positions between it and regionswith properties defining the outer boundaries of the interatrial septum.

Procedure Schema

At block 134, in some embodiments (FIG. 1C), the target selection 212A,selecting an intrabody region, is provided.

Optionally, the method of FIG. 1A continues at block 132. Alternativelyor additionally, the method of FIG. 1D begins at block 132 with thereceipt of information including target selection 212A. In FIG. 1D,target selection 212A is optionally produced as described in relation toFIG. 1A; or is otherwise provided; for example as a direct indicationthrough a user interface, as an element defined along with procedureschema 204B, or from another source. The main difference from block 130is that the selection operation of block 132 selects an action (outputas selected action 212B), rather than an identification of a region.

Inputs to block 132, in some embodiments, include operational context210, measurement data 206, and procedure schema 204B. Optionallyanatomical schema 204A (e.g., the anatomical schema 204A used at block130) is also included as input. However, procedure schema 204B mayitself be understood as a particular type of anatomical schema 204Adefined as a data structure comprising rules, in which the rules thatrelate and characterize different anatomical identities are alsoprovided with indications (derived from rules applied to inputs) of whatactions should be performed on regions having those anatomicalidentities in the context of a particular procedure and/or phase of aprocedure. Herein discussions of aspects of an anatomical schema 204Ashould be understood to apply also to a procedure schema 204B, except asotherwise noted.

For example, the action associated with a PFO in a procedure schema 204Bmay simply be to pass a catheter probe through the open hole, while theaction associated with a closed fossa ovalis may be to penetrate it byneedle and/or the use of an ablation probe. In this case, the identityof the target selection 212A of an intrabody region (open or closedhole) interacts with the operational context 210 (transseptalpenetration) to select alternate options encoded by the procedure schema204B. In some embodiments, the selected action 212B is subject to moredetailed control—for example, if an ablation-assisted transseptalcrossing is selected, the selected action 212B optionally comprisesspecification of ablation parameters to be used, which may vary, forexample, based on the measured and/or anticipated thickness of the fossaovalis.

In some embodiments, selected action 212B is provided as an indicationto an operator which may be treated by the operator as an option,suggestion, and/or recommendation. In some embodiments, selected action212B is automatically used by a system to set parameters for the nextoperation (optionally while maintaining an available option for theoperator to override the parameters. In some embodiments, selectedaction 212B is begun automatically by the system as soon as somecriterion is met—for example, ablation is optionally begun (e.g., withprior operator permission) as soon as the system reaches somepredetermined degree of confidence that the catheter probe is currentlyin contact with the true fossa ovalis.

Target/Action Selection within a Procedure

Reference is now made to FIG. 1B, which is a schematic flowchart of theuse the method of FIG. 1A within the context of a procedure, accordingto some embodiments of the present disclosure.

In some embodiments, a target action is to be performed on some targetedintrabody region. It is referred to as “target action”, since anintended (targeted) result and/or a general class of planned action maybe known, with how to accomplish that result and/or how to preferablycarry out the planned action at least partially to be determined. Atblock 102, in some embodiments, a determination is made as to whetherthere is currently available a valid procedural context based on whichfurther processing can proceed. A “valid” procedural context is one thatis appropriate to the target action, and sufficiently well-characterizedas to allow planning and performing the target action. If yes, theflowchart continues at block 106. Otherwise, flow continues to block104, at which a context is set.

FIG. 1B introduces an optional distinction between two aspects ofoperational context 210—anatomical context 210A and procedural context210B. There need not be a sharp distinction implemented between thesetwo. At least for purposes of description, however, anatomical context210A may be understood to comprise information describing the “where” ofthe current context—for example, where a catheter probe is located,and/or where a current target intrabody region of the catheter (e.g., aregion targeted for ablation) is located. Procedural context 210Bdescribes the “what” of the current context, for example, what a goal ofa current phase of a procedure is (or other features of the currentprocedure phase). Optionally the two types of context are intermingledin their use and/or definition. Optionally, only one of the contexttypes is used and/or defined. For example, in a defined proceduralcontext, all information about anatomical context is optionallysubservient to “what to do next”. An interatrial septum, for example, isoptionally treated as only relevant during the phase of the procedurewhere it becomes a target intrabody region for the target action ofcrossing it. This perspective optionally allows taking a focusedapproach to defining “context”, which has the potential advantage ofcontrolling complexity. On the other hand, the approach can be brittle,since if a procedure leaves the main path of the procedure (e.g., byaccident), there may not be a well-defined way to guide a return.

“Setting” a context 210A and/or 210B is optionally manual, automatic, ora blend of the two. An example of manual context setting is to simplyhave a user inform a system, e.g., that the procedure is now in someparticular phase (related to procedural context 210B), a catheter is nowin some particular place (related to anatomical context 210A), and/or aparticular goal of the current phase has now been reached (again, morerelated to procedural context 210B). Then the system can set a newcontext, based on that input. The input can be, for example, via userinterface 40, for example as described in relation to FIG. 2A.

In an example of automatic context setting, a system is optionallyconfigured to recognize a context based on automatically acquiredmeasurement data 206 (for example, but not necessarily, in conjunctionwith the use of one or more rules of an anatomical schema 204A). Forexample, after sufficient exploration of a right atrium (withoutnecessarily knowing that it is a right atrium), a system optionally hasavailable to it sufficient information to constrain a catheter probe asbeing within a chamber of a certain minimum size, and connected to twolarge, oppositely situated blood vessels. Optionally, a rule of ananatomical schema 204A is defined so that these characteristics uniquely(or at least probabilistically) indicate that the probe is indeedlocated within a right atrium. Optionally (for example, based on thelocation of the probe, its entry point, and the positions of the twoblood vessels), the system is also able to determine in what directionfrom the probe lay other potential target features of the right atrium.Such features could be, for example, the interatrial septum, the openinginto the coronary sinus, and/or the plane of the tricuspid valve. Insome embodiments, manually provided “seed” context is used to orient thesystem, after which acquired data are matched to suitable anatomicalidentities defined by application of rules of the anatomical schema 204Abased on sequential encounters during a procedure. For example,catheters passing in from the jugular vein or the femoral vein shouldenter the heart itself in different locations, so that data indicatingentry to a heart chamber would be interpreted differently in each case.

At block 106, in some embodiments, a target estimator (which may beconsidered as a type of rule defined by an anatomical schema 204A) isselected based on the contexts (anatomical and procedural). Thisselection of an estimator may be one of the operations performed inblock 130 of FIG. 1A. That is, the target intrabody region may beselected in block 130 of FIG. 1A using the estimator selected at block106 of FIG. 1B. In some embodiments of the invention, the types ofmeasurement data 206 used in target intrabody region selection, as wellas how that data is used, can be very different depending on the currentcontext. From an operational context within the right atrium, forexample, an estimator for finding the entry to the coronary sinus (as atarget intrabody region) should look for different characteristics thanan estimator for finding the fossa ovalis (as a different targetintrabody region). Knowing the current anatomical and procedural context210A, 210B (in this case, it is procedural context 210B that isdistinguishing) potentially allows the correct estimator to be selected.

At block 108, in some embodiments, data (that is, data corresponding tomeasurement data 206) is collected, for example as a catheter probe ismoved around within the general vicinity of the target tissue regionbeing sought. As data is collected, it is possible that the operationalcontext will change (intentionally or by accident); so at block 110,operational context is periodically updated based on the samemeasurement data 206. At block 112, if the operational context is nolonger valid for the current target estimator (appropriate to the targetaction, and sufficiently well-characterized as to allow operation of theestimator), flow returns to block 104, where a new operational contextis determined (or verified), and that part of the process begins again.Otherwise, at block 114, the estimator selected at block 106 is used inan attempt to estimate where the current target is and/or what specifictarget action to take (as appropriate).

The estimate attempt may or may not succeed; for example, there may beinsufficient data to make a good early estimate. At block 116, adetermination is made as to whether the estimate result should betreated as reliable. If not, more data is collected at block 108.Otherwise, the flowchart proceeds to block 118, at which an action on atarget is made. Either the action, the target, or both may be specifiedfrom the results of block 114 (with the operator tacitly responsible foraccepting the specification of ablation parameters to be used, andsupplying whatever detail may be missing from the specification).

At block 120, a determination is made as to whether the procedure hascompleted or not. If not, flow returns to block 104, at which a newcontext is potentially set. Otherwise, the flowchart ends.

Examples of System Embodiments

System Overview

Reference is now made to FIG. 2A, which schematically illustrates asystem 500 for use in performing the methods of FIGS. 1A-1B, including aschematic representation of a patient body 2, according to someembodiments of the present disclosure.

At the core of system 500 (for purposes of the present descriptions) isa block representing estimator services 22. This block is described inmore detail in relation to FIG. 2B. The estimator services areoptionally implemented by a computer processor programmed to acceptinputs and provide outputs as described, for example, in relation toFIGS. 1A-1B and/or 2B. In some embodiments, inputs to estimator services22 comprise anatomical/procedure schema 204 (which may comprise one orboth of anatomical schema 204A, and procedure schema 204B). The otherconnections leading into estimate services 22 comprise examples ofvarious sources of measurement data 206.

As an input to estimator services 22, user interface 40 may be used toset context and provide other user-generated selection data, for exampleas described in relation to block 104 of FIG. 1B. User interface 40 alsofunctions as an output for, among other functions the system mayrequire, indications provided as estimator results 212 of estimatorservices 22 (e.g., target selection 212A and/or selected action 212B ofFIG. 1A).

Other inputs provided to estimator services 22 shown in FIG. 2Bemphasize the role of an intrabody probe 11 of a catheter 9 in sensingvarious parameters for use in the operations of estimator services 22.It is to be understood that other input sources are optionally used; forexample, as described in relation to block 206 of FIG. 1A. Electricalfield generator/measurer 10 is provided as a general purpose blockcovering all electrical sensing functions. Optionally, it is implementedas a plurality of sub-modules. In some embodiments, a major function ofelectrical field generator/measurer is to generate and sense electricalfields 4 for use in navigation, for example, using pairs (and/or otherconfigurations) of body surface electrodes 5 (only one body surfaceelectrode is shown in the schematic drawing). In some embodiments,navigation comprises detecting voltages using electrodes 3 of probe 11as they move through a plurality of crossed (e.g., approximatelyorthogonal) time-varying (e.g., at radio frequency) electrical fields.Each voltage is distinguished, for example, on the basis of frequency.Optionally, the crossed fields are treated as coordinate axes,optionally transformed as necessary to produce 3-D spatial coordinates.While body surface electrode-generated fields are used in FIG. 2A as anexample, fields used for electrical navigation are optionally producedfrom other sources; for example, from intrabody electrodes located neara body cavity 50 to be navigated (e.g., in the coronary sinus forcoronary navigation requirements). Optionally, the electrodes of probe11 itself are used to both produce and sense electrical fields, and thesensed voltages treated more as “tags” characterizing differentlocations than as coordinates on coordinate axes.

In some embodiments, measurements made by electrical fieldgenerator/measurer 10 are relayed to position services module 21(optionally implemented as software running on a processor). By whatevermethod is appropriate to the configuration of the system, positionmeasurement system 24 converts the voltage measurements from the probeinto probe positions, while map updating module 23 uses these positionsto generate a map of the body cavities which probe 11 navigates. Overthe course of a procedure, and in particular for regions which probe 11visits exhaustively, there may be a highly detailed map generated.However, this condition of dense visitation potentially does not hold(and/or holds at the cost of inconvenience and procedure delay) for allregions, and anyway there is potentially a significant period of timethat passes before high-resolution map is available. Nevertheless, thepositions and maps created and/or maintained by position services module21 are provided as inputs to estimator service module 22, in someembodiments, as a source of data on which target and/or actionestimators operate. Optionally, but not necessarily, this data isprovided in the form of a current best estimate of anatomical geometry208. Optionally, anatomical geometry 208 is estimated based on resultsof a prior catheterization procedure. Optionally, anatomical geometry208 is estimated at least in part and/or initially based on currently orpreviously acquired imaging data, for example, imaging by CT, MRI, NM,ultrasound, X-ray, or another imaging technique. Optionally, anatomicalgeometry is estimated at least in part and/or initially based onanatomical atlas information.

The data produced by electrical field generator/measurer 10 optionallyinclude data other than that which serves as a direct basis for measuredspatial position navigation. In particular, electrodes 3 may be operatedto obtain data influenced by the local electrical environment of tissue,for example dielectric property data; or more generally, differences inimpedance or other basic electrical properties as a function of localtissue environment. Two types of anatomical features which areparticularly distinguishable from such data are approaches of anelectrode probe 11 to tissue walls, and the relative thickness of thosewalls as electrode probe 11 moves along them. This allowsdistinguishing, for example, more confined cavities (e.g., passagesinto/out of body cavity apertures 51, 52, 54) from more open cavities,and thicker walls from thinner ones (e.g., thin wall feature 53). Suchelectrical properties and their uses are described in connection withembodiments of specific applications described herein, for example, inrelation to FIGS. 4A-4C, 5, 6, 7A-7B, 8, 9A-9D, 10A-10B, and 11 herein.

In some embodiments, one or more non-electrode sensors 14 is optionallyprovided, either as an integral part of probe 11 (as shown), or as partof an auxiliary probe used with it. Such a sensor may comprise, forexample, a force and/or temperature sensor. Data from such sensors isoptionally collected by other sensor interface controller(s) 15, andprovided to estimator services 22 as another form of input.

In some embodiments of the invention, probe 11 comprises one or moreelements 8 supporting one or more treatment modalities. Examples includeelements for cryoablation (balloon and fluid conduits, for example), oneor more RF ablation electrodes, injectable substances and theirinjection means (needle), or another treatment modality. In someembodiments, details of the operation of treatment probe energycontroller(s) 13 are provided to estimator services 22, for example toassist in the evaluation of changes produced as a result of manipulationvia element 8. Optionally, treatment parameters' under the control ofcontroller 13 are controlled and/or suggested based on outputs fromestimator services 22 (for example, in embodiments where an output ofestimator services 22 comprises parameters of a selected action 212B).

Estimator Services

Reference is now made to FIG. 2B, which schematically represents inputsand operations of an estimator services module 22, according to someembodiments of the present disclosure.

In some embodiments, inputs to estimator service module 22 include hintinputs 202, anatomical/procedure schema 204, measurement data 206,and/or anatomical geometry 208.

In some embodiments, hint inputs 202 comprise one or more forms ofnon-measurement data which are used by estimator services 22 in settingcontext which may help in selecting an estimator (for example asdescribed in relation to block 104 of FIG. 1B), and/or provideinformation used by an estimator (e.g., information used by selectedestimator 201) to produce an estimator result 212. In some embodimentsthe hint inputs comprise explicitly provided inputs from an operator,for example, inputs specifying a location of probe 11, a port of entryof probe 11, which probe 11 of an optional plurality of probes is beingused, operational phase of a current procedure, a selection amongpotential anatomical variants, or another input.

In some embodiments, hint inputs 202 comprise information implicit tothe choice of system configuration and/or procedure. For example,estimators which rely on electrical field navigation-type positioninputs are normally unavailable for selection by estimator selector 203if electrical field navigation is not being used. Hints can alsoinclude, for example, specification of the point of initial access of acatheter to a body (e.g., femoral vein or jugular vein) and/or detailsof anatomy (for example, the presence of variant anatomy structures)which may be known from previous data such as prior catheterizationand/or imaging procedures.

Anatomical/procedure schema 204, in some embodiments, comprises one ormore rule-defining data structures configured as described, for example,in relation to FIG. 1A, and/or as described in relation to the schematicexample of FIG. 3A.

Measurement data 206, in some embodiments, comprises data from one ormore sources of measurements, for example one of the sources listed inrelation to block 206 of FIG. 1A, and/or described in relation to thevarious data collecting elements (e.g., electrical fieldgenerator/measurer 10, other sensor interface/controller(s) 15,treatment probe energy controllers 13, and/or position measurementsystem 24) of FIG. 2A.

Anatomical geometry 208, in some embodiments, comprises a currentestimate of patient anatomy in a region of interest, for example asdescribed in relation to block 204 of FIG. 2A.

In some embodiments, estimator services 22 comprises two mainoperations: (1) selection of an estimator 201 by an estimator selectormodule 203 from among a pool of available estimators 200, and (2) use ofthe selected estimator 201 to produce an estimator result 212, based oncurrently available inputs. These operations are described, for example,in relation to FIG. 1B. It is noted that in some embodiments there isalso maintained by the estimator services 22 an operational context 210,comprising one or both of a current anatomical context and a proceduralcontext.

Examples of Anatomical Schema

Reference is now made to FIG. 3A, which schematically representsselected anatomical relationships encoded by rules of an anatomicalschema 204A, according to some embodiments of the present disclosure.Reference is also made to FIG. 3B, which illustrates some of the leftatrium 301 features mentioned in FIG. 3A in an “unwrapped” view of theleft atrium, according to some embodiments of the present disclosure.

The portion of the anatomical schema 204A illustrated in FIG. 3Aemphasizes relationships among regions of different anatomicalidentities that relate to the atrial chambers of the heart (that is,rules governing aspects of their spatial relationships to one another).It is to be understood that the diagram of FIG. 3A is a visualrepresentation of logical relationships which would normally beotherwise encoded (e.g., as XML, JSON, and/or a binary format), forexample as described in relation to block 204A of FIG. 1A. Elements ofthe diagram illustrate examples of features mentioned in thatdescription, for example relationships of position and composition.Selected examples of the use of property features are also discussedbelow in relation to particular anatomical identities.

In some embodiments, an anatomical schema 204A may include coverage ofall or any suitable fragment of the anatomical structures shown in FIG.3A, and optionally different or additional anatomical structures.Potential advantages of a more complete anatomical schema 204A includecoverage of more situations (e.g., more navigation regions, differentavailable data, more types of anatomical variants), and/or increasedreliability of automatic inferences made using rules of the schema(e.g., because more lines of evidence potentially converge to confirm anidentification of a target intrabody region). A more complete anatomicalschema 204A may also be useful for uninterrupted control and/ormonitoring of the flow of operations throughout a larger section of theoverall procedure, for example for support of multi-chamber operations.In contrast, a relatively fragmented anatomical schema may still be ofvalue for providing assistance during particularly difficult and/orerror-prone phases of a procedure. For example, a fragmented anatomicalschema may comprise just rules for identifying a fossa ovalis targetwithin an interatrial septum, assuming prior localization of theinteratrial septum. As previously noted, a procedure schema 204B isoptionally implemented as a narrowly defined anatomical schema, whereineach anatomical identity in the schema is provided with informationparticularly tailored to progressing the procedure from one phase to thenext. Optionally, identities shown in FIG. 3A as “anatomical identities”are recast as “procedural identities”, focusing on phases of navigationand/or intervention such as “enter right atrium”, “cross the IAS”,“ablate” and the like—in this case, anatomical identities are optionallyentities subservient to the exigencies of each sequential operationalphase of the procedure.

For brevity, in the descriptions of FIG. 3A that follow, schema entriescomprising collections of rules for particular anatomical structures(anatomical identities) are referred to by common names for thoseanatomical structures. However, it should be understood that suchreferences with respect to FIG. 3A are actually to the portion of theanatomical schema data structure that pertains to the actual anatomicalstructure mentioned, not the anatomical structure itself.

Beginning with schema entry for the right atrium 303, FIG. 3A shows thatthe right atrium 303 is directly connected to typical and/or variantright atrium features such as tricuspid valve 318 (leading to the rightventricle 305), inferior vena cava 316, coronary sinus 312, superiorvena cava 320, interatrial septum 301, and Eustachian valve 314. Thislist of connected elements is not necessarily exhaustive, and any givenimplementation of an anatomical schema optionally adds or removes schemaentries as appropriate for the particular procedure(s) which are to besupported. Several of the schema entries of FIG. 3A are indicated withdoubled overlapping enclosures. This is to indicate the optionalpresence of variant anatomies, the detection and encoding of which isdescribed herein with respect to some selected examples. Anotherconvention of FIG. 3A is the use of partial boxes to indicate theoptional inclusion in some embodiments of additional schema entries notshown in FIG. 3A, for example unnamed features 305A, 312A, 307A, and316A, connected their correspondingly numbered (without the terminal“A”) anchoring schema entries.

One example of an anatomical variant is Eustachian valve 314, a valve ofthe inferior vena cava (IVC) which is large in the fetal stage, andplays an important role in fetal circulation as it directs oxygenatedblood from the maternal placenta directly across the patent foramenovalis into the left atrium thereby reaching the left ventricle(avoiding the lungs) and being pumped, e.g., to the brain. In someembodiments, the maintained and/or enlarged presence of this valve in anadult patient is associated with increased risk of right to leftparadoxical shunt of emboli across the PFO (stroke). In some embodimentsof an anatomical schema, a criterion for noting the presence of anenlarged Eustachian valve comprises a finding of interference withmovements and/or positioning of a probe 11 in the region of the IVC(particularly compared to the superior vena cava, SVC). In someembodiments, such a criterion comprises a finding of otherwiseunexpected fluctuations in impedance properties consistent with contactwith a wall or flap, in a place where a canonical anatomy would be freeof such fluctuations. Meeting one or both of these criteria in a certainlocation optionally not only sets that location “Eustachian valve”, butalso helps to identify a nearby region having, for example, impedanceand/or navigationally restricting features of a blood vessel inlet asbeing more specifically the inlet to the right atrium of the IVC. Thisin turn allows the deductive inference that a second such blood vesselinlet is the SVC. From this the orientation of the right atrium is nowknown, allowing localization of the direction in which the interatrialseptum 310 lies, and, at least along the IVC/SVC axis, something aboutits extent. Similarly, the general position of features such as thecoronary sinus and tricuspid valve can be automatically deduced(crossing the tricuspid valve, for example, is optionally noted fromchanges in intra-cardiac ECG), and any “sinus like” or “valve like”features in those positions assigned to be actually the appropriatefeature with a high degree of confidence.

Similar chains of deduction can be built up from different startingpoints and/or hints. For example, if it is known that thecatheterization procedure began from a femoral vein, then the IVC/SVCdistinction can be inferred based on the vein-like aperture, throughwhich the catheter first enters the right atrium. Entry to the rightatrium itself may be detected by such features as how many and/or whatrelative size of apertures lead from it (once it is mapped to sufficientcompleteness), how far a probe can move across it in one or moredirections before encountering impedance changes characteristic of awall encounter, an impedance reading while in the heart chamber whichindicates that all tissue walls are far away, impedance or otherelectrical readings which show a pronounced heartbeat cycle-dependentfluctuation, detection of electrical impulses propagating through thewalls of the chamber, and/or another distinguishing property of theright atrial chamber environment measurable by a probe situated therein.Any or all of these types of measurement-based indications and/orlogical deductions are optionally provided as explicitly encodedfeatures of an anatomical schema 204A. However, in some embodiments,some or all of these indications and/or logical deductions are found andencoded implicitly, for example based on supervised machine learningtechniques, for example as described in relation to FIG. 3C.

Another situation for which an anatomical schema may provide guidance isin the location of a fossa ovalis (or PFO), for example as described inrelation to FIG. 5 , herein. With respect to the structure of theanatomical schema, it is noted for now that the fossa ovalis 311 isoptionally encoded as an anatomical sub-identity of the interatrialseptum 310. For purposes of locating the actual fossa ovalis, a searchstrategy optionally proceeds first by finding some part of theinteratrial septum, and then by further search locating the fossa ovalis311 itself.

Continuing from the schema entry for the fossa ovalis 311, theanatomical schema of FIG. 3A also comprise a schema entry for leftatrium 301. Visual appearances of some of these features can be seen inan unwrapped view of the internal lumenal surface of a left atrium shownin FIG. 3B (in FIG. 3B, reference characters label anatomical featuresas such using the same numbering scheme applied to the anatomical namesapplied more narrowly to schema entries in the descriptions of FIG. 3A).

In addition to the fossa ovalis 311 and interatrial septum 310, leftatrium 301 is also connected to several other features which line (ormay line) its interior lumenal wall, including the left atrial appendage(LAA) 319, the pulmonary veins 302, the so-called (and optionallypresent in variant forms of various sizes) warfarin ridge 306, and themitral valve 308 (which leads to the left ventricle 307, which has notbeen detailed in the figure).

Of particular interest as an example is the potentially variant anatomyof the pulmonary veins, which can potentially be present as thecanonical 4-vein variant (pulmonary veins (PV) 330, 331, 332, 333), orin another variant form 304 such as a three-vein variant. In someembodiments, an anatomical schema is adapted to automatically selectfrom among possible variants based on numbers of aperture featuresactually encountered, and/or based on where aperture features areencountered (for example, encountering an unusually large ostium in aposition intermediate to the canonical four-vein positions of two PVs isoptionally treated as evidence that the three-vein anatomical variant ofthe anatomical schema should be used.

Thus, each schema entry for a certain anatomical identity is optionallylocatable based on at least one of the following types of information:

-   -   How it is positioned and/or oriented with respect to other        identified anatomy parts;    -   How it is positioned and/or oriented with respect to a probe        being used in the procedure;    -   What sorts of properties (for example, impedance properties, or        any other property for example as described in relation to FIG.        1A) it is expected to have (even if those properties as such are        only partially identifying, they may work together with        information about the overall anatomical context to form a full        positive identification)    -   What sorts of properties help to distinguish relevant anatomical        variants from one another.

In some embodiments, as different regions of an anatomy areautomatically provided with anatomical identities, a system indicatesthese identities to a user through user interface 40. Optionally,anatomical identities (previously and/or currently provided as targetselection 212A, for example) are associated with a degree of confidence,which potentially may be increased by the acquisition of additionaldata. Optionally, indications can be manually set by system operators.Optionally, automatically determined indications can be edited and/oroverridden by system operators. Manual identification input may be used,for example, as supervised results paired with training data collectedfor use in machine learning of associations that produce target and/oraction estimator results 212 from input measurement data 206.

In some embodiments, anatomical identities are shown on user interface40 as tags, for example, character abbreviation tags, colored spheres(with associated dictionary), fully colored and/or textured regions ofanatomical surfaces (e.g. heart chamber and/or vascular wall), shadingeffects to simulate surface features (e.g., bump mapping to highlight anidentified region of a fossa ovalis), and/or special lighting effectsapplied to a rendered view approximating the anatomical geometry. Forexample, lighting may be simulated within the PVs and/oratrial-ventricular valve planes to mimic the color Doppler schemeaccording to direction of blood flow (e.g. blue-away, red-towards, oranother convention). Optionally, tags that apply to hidden surfaces (forexample, coronary sinus ostia) are visualized by, for example, changingthe opacity with which an anatomical geometry is displayed, and/orapplying a clipping plane to the display. Optionally, tag displayeffects are modulated to indicate confidence, for example, made moretransparent, less saturated in color, differently textured, made morediffuse, or otherwise modified. Optionally, confidence is simplydisplayed as graphical indications like bars, dots, and/or numbers.

Actions (for example, selected action 210B) selected on (e.g.recommended for) a target region are optionally signaled by arrows,glowing and/or pulsing markers, or other signals. Certain types ofactions are typically accompanied by changes in shape or position whichcan be inferred from non-imaging readings. For example, crossing of thefossa ovalis may be accompanied by characteristic “tenting” for exampleas described in relation to FIGS. 4A-4B. In some embodiments, thesechanges are simulated in a display for the user, wherein the simulationis synthesized on the basis of available non-imaging data.

Machine Learning Results Used with Anatomical Schema

Reference is now made to FIG. 3C, which is a schematic flowchart of theuse of machine learning to establish at least some aspects of ananatomical schema 204A, according to some embodiments of the presentdisclosure.

Supervised machine learning comprises a family of techniques known inthe art which are applicable to infer a function from a set of trainingexamples (for example, training examples 361 of FIG. 3C). The trainingexamples include pairs of inputs and their expected outputs (the outputsare provided as supervisory signals, for example supervisory signals 363of FIG. 3C). The result of the machine learning is a function or otherdata structure which can be used to relate non-training inputs to newoutputs in a way that (given a sufficient training set) followsinput-output correlations found in the training examples.

In some embodiments, an anatomical schema 204A is built at leastpartially on the basis of machine learning results. In some embodiments,preparation of the training examples is performed on the basis of ananatomical schema framework which already includes many of the generalfeatures of the anatomical schema (e.g., which anatomical features areadjoining to and/or contained by other features), but also hasplaceholder and/or empty functions for at least some of the functionsthat relate recorded measurement data to anatomical identities and/orrecommended procedure actions. Machine learning results are optionallyused to supply practical versions of these functions.

Measurement data 206 (described, for example, in relation to FIG. 1A) islargely what comprises the “input” side of the training examples, thoughthe training example input may also be considered to include such thingsas patient history and other patient data, imaging data obtained outsideof the procedure itself, and/or procedure design and parameters. Aspreviously noted, in intervention procedures performed over catheter byindirect visualization, nearly all of the inputs and many outputsgenerated during a procedure are available in the same digital formoriginally available to practitioner.

Supervisory signals 363, in some embodiments, comprise at least one of:

-   -   operator's anatomical identifications 354 (optionally, these are        provided by the operator in real time or corrected by the        operator post-procedure. Correction may be applied to operator's        provided identification and/or to outputs of a previously        available anatomical schema);    -   operator's actions 356 (what the operator actually did in a        certain input context may be considered as an output reflecting        the particular expertise of the operator);    -   operator's other annotations 358 (for example, indications by an        operator as to which particular parts of measurement data 206        were most relevant to anatomical identifications and/or        actions);    -   post-processing annotations 360 (e.g., corrections of errors,        linkage of outputs and inputs which are separated in the raw        data such as ablation validations, annotations to interpret data        and/or actions in terms defined by the anatomical schema        framework 350); and/or    -   procedure outcomes 362 (e.g., results of a procedure which may        only become known after the procedure itself is complete).

At block 366, in some embodiments, the training examples are optionallyfurther processed so that appropriate epochs of a procedure are assignedto be associated with the correct schema entries of the anatomicalschema framework 350 (e.g., annotated so that they are associated withtheir correct anatomical and/or procedural context). The result of this,and any optional further post-processing such as normalization, isprovided as post-processed training examples 352.

At block 368, the machine learning itself is performed, based on thepost-processed training examples 352. Optionally, any suitable machinelearning technique is used, for example, artificial neural network, backpropagation, Bayesian statistics, case-based reasoning, decision treelearning, inductive logic programming, Gaussian process regression,group method of data handling, kernel estimators, learning classifiersystems, multilinear subspace learning, naive Bayes classifier, maximumentropy classifier, conditional random field, nearest neighboralgorithm, probably approximately correct learning, symbolic machinelearning algorithms, subsymbolic machine learning algorithms, supportvector machines, minimum complexity machines, random forests, ensemblesof classifiers, ordinal classification, data pre-processing, statisticalrelational learning, and/or another machine learning technique.

At block 370, in some embodiments, the results of the machine learningat block 368 are assigned to the anatomical schema framework to producean updated anatomical schema 204A.

Examples of Procedure Operations Used with Automatic Target/ActionSelection Interatrial Septum Crossing

Reference is now made to FIGS. 4A-4C, which schematically representcrossing by a catheter probe 11 from a right atrium 303 across aninteratrial septum 310 to a left atrium 301 via a fossa ovalis 311,according to some embodiments of the present disclosure.

In FIG. 4A, probe 11 has found fossa ovalis 311, and is positionedagainst it. In FIG. 4B, probe 11 is pressing against fossa ovalis 311,causing “tenting” of the interatrial septum 310. In FIG. 4C, probe 11has penetrated the fossa ovalis, releasing the tenting, and leavingprobe 11 temporarily embedded half-way through the interatrial septum310.

Different methods may be used to help encourage the crossing of a probe11 at a crossing location as shown. Descriptions in relation to FIG. 11, herein, describe how ablation by a probe (e.g., RF ablation) may beused to assist crossing, potentially allowing a “single catheter”procedure for ablation to treat atrial fibrillation. Descriptions inrelation to FIG. 6 , herein, describe electrically monitored use of aneedle to cross the interatrial septum.

Reference is now made to FIG. 5 , which is a schematic flowchartdescribing a method of locating a fossa ovalis, according to someembodiments of the present disclosure.

At block 510, in some embodiments, a catheter probe 11 is navigated intocontact with the interatrial septum (IAS). Discovery of the position ofthe IAS, for example with respect to the orientation of the IVC and SVC(optionally with assistance from the identification of the Eustachianvalve) is provided in descriptions of FIG. 3A, in relation to an exampleof a schema entry for an interatrial septum 310. It is noted inparticular that in some embodiments, a full right atrium map isoptionally not generated—it is potentially sufficient to find the IAS,and scan it (by probe movements) in the general region where the fossaovalis is expected to lie.

At block 512, in some embodiments, the catheter probe 11 is moved overthe IAS while making dielectric measurements. It is generally notnecessary to completely dielectrically map the IAS.

At block 514, in some embodiments, the foramen ovalis or patent foramenovale (PFO) (according to which is present) is identified.

In some embodiments, a fossa is identified based on a combination ofvoltage and/or impedance signals measured from probe electrodes 3, andgeometrical considerations. The fossa is characteristically the thinnestzone in the septum (although in rare occasions it is lipomatous andthickened). A typical dielectric signature will vary from surroundingwall over a characteristics diameter of about 5-10 mm. Geometrically,the fossa is located about halfway between the SVC and IVC on the septalwall, between the septum primum and the septum secundum. The anatomicalvariant of an adult PFO may additionally or alternatively be identifiedas an open transseptal tract because the catheter probe simply crossesinto the left atrium when it is pressed against the region of the PFO.It is noted that initially small 3-4 mm PFOs potentially increase indiameter with aging and can become stretched up to 7-10 mm (resembling asmall to moderate atrial septal defect).

Monitored Needle Interatrial Septum Crossing

Reference is now made to FIG. 6 , which is a schematic flowchartdescribing a method of crossing a fossa ovalis using an electricallymonitored needle, according to some embodiments of the presentdisclosure.

Electrical monitoring of interatrial septum crossing using aBrackenrough needle and a NavX system (EnSite) has been described basedon spatial position monitoring (Sumit Verma and Mark Borganelli,Real-Time, Three-Dimensional Localization of a Brockenbrough Needleduring Transseptal Catheterization Using a Nonfluoroscopic MappingSystem, J. Invasive Card., 18:7 (2006)). In some embodiments of thepresent disclosure, features of the electrical changes which occurduring this penetration (not necessarily observations of position perse) are used to generate a visual representation of the procedure whichevokes the “tenting” phenomenon which may be observed, e.g., underdirect imaging visualization of a transseptal penetration.

The flowchart begins, and at block 610, in some embodiments, a catheterincluding a transseptal needle encased in a sheath is navigated to theregion of a fossa ovalis. The needle itself (which is quite long, e.g.,about 70-110 cm long, so that it may extend out of the body even withits tip inside the heart) can be used as a sensing electrode byelectrically connecting it to, e.g., electrical field generator/measurer10. Optionally, a proximal part of the needle is connected using analligator clip through the pin-box to the system, converting it to along, though insulated along its length, unipolar electrode.

In some embodiments, the transseptal needle itself is used to find thefossa ovalis, for example, as described in relation to FIG. 5 .Optionally, the fossa ovalis is found separately from the action ofcrossing the fossa ovalis using the needle.

At block 612, in some embodiments, the needle is gradually extended fromits sheath. The progress of the operation is optionally tracked bynoting the changes in electrical signal as more and more of the needleis protruded from the electrically insulating sheath.

At block 614, in some embodiments, detection is made as to whether ornot a sudden jump in electrical signal amplitude has occurred.

If not, optionally (at block 615), a display (e.g. on user interface 40)presents penetration progress to an operator by imitating the typical‘tenting’ of the IAS before a successful puncture. Flow continues with areturn to block 612.

Otherwise, at block 616, the jump is interpreted as a successfulpenetration. The “tenting” display is optionally returned to the IAS'sresting position, but with the penetration needle now shown crossing theIAS. The flowchart ends.

Monitored Cryoballoon Ablation

Reference is now made to FIGS. 7A-7B, which schematically representstages in cryoablation including insertion of a lasso catheter probe 711into a pulmonary vein 331 of a left atrium 301, and conversion of bloodflow 705 into blocked flow 706 as a cryoballoon 713 is pressed firmly upagainst the ostium leading into pulmonary vein 331, according to someembodiments of the present disclosure. Reference is also made to FIG. 8, which is a schematic flowchart describing a method for electricalmonitoring of the flow blockage 706 shown in FIGS. 7A-7B, according tosome embodiments of the present disclosure.

At block 810, in some embodiments, the looped (lasso) region of acatheter probe configured like the lasso-and-balloon probe 711 of FIG.7A is inserted to a pulmonary vein (PV). At block 811, the PV anatomy ismapped, for example to verify that the geometry is of an appropriatesize and shape to allow use of the cryoballoon 713 to make a completeablation around the ostium of the PV. In some embodiments, mapping thePV anatomy may include moving one or more electrodes of probe 711 whiletracking its position, and determining the limits of its movement and/orpositions at which the electrodes experience a change in measuredimpedance indicative of contact with and/or proximity to a cavity wall.

At block 812, in some embodiments, the cryoballoon is optionallyinflated, and the catheter probe 711 positioned in a state like thatshown in FIG. 7A—balloon inflated, but not yet positioned to pressagainst the PV ostium. Alternatively, in some embodiments, the balloonis advanced into position while remaining deflated, and is graduallyinflated in place.

At block 814, the cryoballoon is advanced towards (and/or inflatedwithin) the PV ostium while electrically monitoring voltages generatefrom electrodes of the lasso catheter probe 711 using those sameelectrodes. During advancing/inflating, at block 816, a check is madefor an occlusion jump in the monitoring data (that is, a relativelysudden change in voltage). Such a jump (for example, a jump of at least3 times the high-frequency noise amplitude occurring, for example,within 100 msec, 200 msec, 500 msec, 1 seconds, or 2 seconds) has beenobserved by the inventors in association with the completion of sealingof the PV ostium by the advancing cryoballoon. In some embodiments, oneor more characteristics of a change in voltage which is recognized inthe check as comprising such a jump are predetermined. For example, thecharacteristics are optionally defined according to their time course,frequency, and/or amplitude. Optionally, the characteristics arepredetermined by use of a machine learning result, e.g., a weightingdata structure created from training examples associated with feedbackcategorizing them as “jump” or “non-jump”. At block 822, if the jump hasnot yet been noted, the flowchart returns to block 814. Otherwise, theflowchart continues at block 818 with cryoablation (e.g., filling of thecryoballoon with cryogenic fluid to induce a preferably circular lesionaround a periphery of the PV ostium). Optionally, after the completionof ablation, electrodes of the lasso probe (or another probe) are used(at block 820) to check the resulting lesion for gaps, for example usingimpedance measurements. An example of data resulting from such a checkin a phantom pig heart is provided in FIGS. 10A-10B. Optionally (notshown) gaps are repaired by additional cryoballoon lesioning and/ortargeted RF lesioning.

A potential advantage of the method of FIG. 8 for monitoring occlusionis to avoid a need for X-ray imaging and/or contrast medium injection toverify that a good balloon-tissue contact has been accomplished.

Reference is now made to FIGS. 9A-9D, which schematically represent testresults of the method of FIG. 8 , according to some embodiments of thepresent disclosure.

FIG. 9A shows changes in sensed voltage at two particular frequencies(of an optional multiplicity of frequencies which may be used), from aplurality of electrodes such as the lasso electrodes of catheter probe711. Results from six electrodes are shown. It may be observed thatthere appears to be a relatively sudden jump at around 18 seconds from acluster of early voltage values to a cluster of later-recorded voltagevalues. These jumps correlate with the moment of sealing contact betweenthe cryoballoon (a Medtronic Arctic Front cryoballoon) and awater-immersed pig heart phantom, as indicated by reduction of fluidflow maintained by a syringe attached to an open tube through thephantom PV to zero.

FIGS. 9B-9C show onset and offset of the voltage jump for a singleelectrode, including a voltage jump in FIG. 9B when flow was stopped bythe cryoballoon (at about 18 seconds), and other jump at about 7 secondsin FIG. 9C when flow was resumed (by deflation/moving of thecryoballoon).

FIG. 9D shows second-by-second correlations between measured flowvelocity (square data points) and the voltage jump signal (diamond datapoints), strengthening the case for a causal association between balloonsealing and the voltage jump.

Reference is now made to FIGS. 10A-10B, which respectively representvisual results of cryoablation in vitro on a muscle tissue preparation1000 (FIG. 10A), and dielectric assessment of the same results (FIG.10B) which reveals a potential gap 1003 in the apparently well-ablatedregion 1001.

Another potential advantage of the method of FIG. 8 is that theelectrodes of the lasso are nearly in position to be repositioned tomeasure the possible presence of ablation gaps, so that remedial actioncan be taken immediately, potentially before the full onset of tissuereactions such as edema which can interfere with the effectiveness ofsubsequent ablation attempts.

The light-colored region 1001 of FIG. 10A is discolored due to previousexposure to cryoablation (the lesion is not circular because of the flatgeometry of the test preparation). However, upon dielectric measurementof tissue properties in the area, it was found that a partial gapindicated in region 1003 remained. Dielectric measurement of tissuelesion properties is described, for example, in International PatentPublication No. WO2016/181318, entitled LESION ASSESSMENT BY DIELECTRICPROPERTY ANALYSIS, and published on Nov. 17, 2016.

Single Catheter Transseptal Access and Left Atrium Ablation

Reference is now made to FIG. 11 , which is a schematic flowchartdescribing a method for single-electrode transseptal penetration fromthe right to the left atria, followed by ablation within the leftatrium, according to some embodiments of the present disclosure.

Blocks 1110-1114, in some embodiments, correspond to blocks 510, 512,and 514 of FIG. 5 .

At block 1110, in some embodiments, a catheter probe 11 comprising atleast a tip electrode configured to act as an RF ablation probe isnavigated to an IAS by any suitable method, for example as described inrelation to FIG. 3A, herein. At block 1112, the probe is moved over theIAS while making dielectric measurements, and at block 1114, the fossaovalis (or patent foramen ovale, according to the anatomy) is identifiedfrom the dielectric measurements. At block 1116, the probe is moved tothe fossa/PFO (if it is not there already). At block 1122, adetermination is made as to whether the ablation catheter probe 11 canalready cross the septum (e.g., because there is a PFO). If not, then atblock 1118, the RF ablation electrode of the catheter is activated toablate at the fossa ovale. Optionally, ablation settings used aresimilar to those used in normal transmural ablation for AF treatment.Optionally, the ablation settings are more aggressive, however, in orderto achieve substantial mechanical weakening of the IAS structure whichis normally preferably avoided in AF lesion treatments. Potentially, theablation weakens the already thin fossa ovalis sufficiently to allow thecatheter probe 11 to penetrate it through the use of blunt force. Fromwhich ever branch of the method, at block 1120, in some embodiments, thecatheter probe is pushed across the IAS. The catheter is navigated intoposition to perform ablation treatments, and at block 1124, in someembodiments, ablation in the left atrium (e.g., ablation to encircle PVswith ablation lines) is performed.

Potentially, crossing the IAS without a transseptal needle isadvantageous economically, e.g., for requiring fewer tools and/or fewertool changes during a procedure. Crossing by applying RF energy isoptionally performed, for example, with a dedicated Baylis system and/ora standard RF generator.

It is expected that during the life of a patent maturing from thisapplication many relevant position tracking methods will be developed;the scope of the term “position tracking” is intended to include allsuch new technologies a priori.

As used herein with reference to quantity or value, the term “about”means “within ±10% of”.

The terms “comprises”, “comprising”, “includes”, “including”, “having”and their conjugates mean: “including but not limited to”.

The term “consisting of” means: “including and limited to”.

The term “consisting essentially of” means that the composition, methodor structure may include additional ingredients, steps and/or parts, butonly if the additional ingredients, steps and/or parts do not materiallyalter the basic and novel characteristics of the claimed composition,method or structure.

As used herein, the singular form “a”, “an” and “the” include pluralreferences unless the context clearly dictates otherwise. For example,the term “a compound” or “at least one compound” may include a pluralityof compounds, including mixtures thereof.

The words “example” and “exemplary” are used herein to mean “serving asan example, instance or illustration”. Any embodiment described as an“example” or “exemplary” is not necessarily to be construed as preferredor advantageous over other embodiments and/or to exclude theincorporation of features from other embodiments.

The word “optionally” is used herein to mean “is provided in someembodiments and not provided in other embodiments”. Any particularembodiment of the invention may include a plurality of “optional”features except insofar as such features conflict.

As used herein the term “method” refers to manners, means, techniquesand procedures for accomplishing a given task including, but not limitedto, those manners, means, techniques and procedures either known to, orreadily developed from known manners, means, techniques and proceduresby practitioners of the chemical, pharmacological, biological,biochemical and medical arts.

As used herein, the term “treating” includes abrogating, substantiallyinhibiting, slowing or reversing the progression of a condition,substantially ameliorating clinical or aesthetical symptoms of acondition or substantially preventing the appearance of clinical oraesthetical symptoms of a condition.

Throughout this application, embodiments of this invention may bepresented with reference to a range format. It should be understood thatthe description in range format is merely for convenience and brevityand should not be construed as an inflexible limitation on the scope ofthe invention. Accordingly, the description of a range should beconsidered to have specifically disclosed all the possible subranges aswell as individual numerical values within that range. For example,description of a range such as “from 1 to 6” should be considered tohave specifically disclosed subranges such as “from 1 to 3”, “from 1 to4”, “from 1 to 5”, “from 2 to 4”, “from 2 to 6”, “from 3 to 6”, etc.; aswell as individual numbers within that range, for example, 1, 2, 3, 4,5, and 6. This applies regardless of the breadth of the range.

Whenever a numerical range is indicated herein (for example “10-15”, “10to 15”, or any pair of numbers linked by these another such rangeindication), it is meant to include any number (fractional or integral)within the indicated range limits, including the range limits, unlessthe context clearly dictates otherwise. The phrases“range/ranging/ranges between” a first indicate number and a secondindicate number and “range/ranging/ranges from” a first indicate number“to”, “up to”, “until” or “through” (or another such range-indicatingterm) a second indicate number are used herein interchangeably and aremeant to include the first and second indicated numbers and all thefractional and integral numbers therebetween.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

All publications, patents and patent applications mentioned in thisspecification are herein incorporated in their entirety by referenceinto the specification, to the same extent as if each individualpublication, patent or patent application was specifically andindividually indicated to be incorporated herein by reference. Inaddition, citation or identification of any reference in thisapplication shall not be construed as an admission that such referenceis available as prior art to the present invention. To the extent thatsection headings are used, they should not be construed as necessarilylimiting.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination or as suitable in any other describedembodiment of the invention. Certain features described in the contextof various embodiments are not to be considered essential features ofthose embodiments, unless the embodiment is inoperative without thoseelements.

What is claimed is:
 1. A method of determining, during a medicalprocedure, an anatomical identity of a first intrabody region which is aregion included in a second intrabody region, the first and secondintrabody regions being, in a body of a patient undergoing the medicalprocedure, the procedure using an intrabody probe, the methodcharacterizing a position of the intrabody probe, and the methodcomprising: receiving data indicating that the intrabody probe isoperating in an operational context, a specification of the operationalcontext including a condition indicative of proximity of the intrabodyprobe to the second intrabody region; receiving input data from theintrabody probe indicating one or more measured properties of the firstintrabody region; wherein the input data is received while the intrabodyprobe moves, and the condition indicative of proximity remainssatisfied; selecting at least one rule for anatomical identificationfrom an anatomical schema, wherein the at least one rule is selected,based on the operational context, from a set of a plurality of differentrules, wherein one or more of said different rules is associated withone or more operational contexts different from and exclusive to saidoperational context; and applying the at least one rule to the inputdata, to determine anatomical identity of the first intrabody region,also while the condition indicative of proximity remains satisfied,thereby characterizing the position of the intrabody probe with respectto the first intrabody region included in the second intrabody region.2. The method of claim 1, comprising associating the anatomical identitydetermined for the first intrabody region to a geometricalrepresentation of the first intrabody region within the second intrabodyregion.
 3. The method of claim 2, comprising displaying the anatomicalidentity determined for the first intrabody region together with adisplay of the geometrical representation of the first intrabody regionwithin the second intrabody region.
 4. The method of claim 1, comprisingguiding navigation of the intrabody probe to the first intrabody region,based on the anatomical identity determined for the first intrabodyregion and the characterization of the position of the intrabody probewith respect to the first and second intrabody regions.
 5. The method ofclaim 1, comprising using the intrabody probe to perform an action uponthe first intrabody region, based on the anatomical identity determinedfor the first intrabody region.
 6. The method of claim 1, wherein theinput data does not include image data.
 7. The method of claim 6,wherein the data indicating a current operational context comprisenon-image data.
 8. The method of claim 1, wherein the input datacomprises electrical measurements from the intrabody region.
 9. Themethod of claim 8, wherein the electrical measurements comprise voltagemeasurements.
 10. The method of claim 8, wherein the electricalmeasurements comprise impedance measurements.
 11. The method of claim 1,wherein the operational context comprises an anatomical location of theintrabody probe.
 12. The method of claim 1, wherein the operationalcontext comprises the nature of the medical procedure.
 13. The method ofclaim 1, wherein at least two of the different rules in the set of rulesare different in one or more parameter value of a same parameter. 14.The method of claim 1, wherein selecting at least one rule based on theoperational context comprises selecting a rule for identifying aparticular target tissue based on the operational context.
 15. Themethod of claim 1, wherein selecting at least one rule based on theoperational context comprises selecting a rule which takes into accountchanges in measurement data based on the operational context.
 16. Themethod of claim 1, wherein said operational context has a firstidentification rule or a first action rule associated to be appliedtherewith, when said operational context is indicated; and wherein saidplurality of operational contexts includes a plurality of additionaloperational contexts, in addition to said operational context, each saidadditional operational context of said plurality of additionaloperational contexts corresponding to a different phase of said medicalprocedure, each of said additional operational contexts havingassociated to be applied therewith at least one identification rule notassociated to be applied with said operational context when indicated,or an action rule not associated to be applied with said operationalcontext when indicated.
 17. A method of determining, during a medicalprocedure, an anatomical identity of a first intrabody region comprisinga fossa ovalis and included in a second intrabody region comprising aninteratrial septum, the first and second intrabody regions being in abody of a patient undergoing the medical procedure, the procedure usingan intrabody probe, the method characterizing a position of theintrabody probe, and the method comprising: receiving data indicatingthat the intrabody probe is operating in an operational context, aspecification of the operational context including a conditionindicative of proximity of the intrabody probe to the second intrabodyregion; receiving input data from the intrabody probe indicating one ormore measured properties of the first intrabody region; wherein theinput data is received while the intrabody probe moves, and thecondition indicative of proximity remains satisfied; selecting at leastone rule for anatomical identification from an anatomical schema,wherein the at least one rule is selected, based on the operationalcontext, from a set of a plurality of different rules, wherein one ormore of said different rules is associated with one or more operationalcontexts different from and exclusive to said operational context; andapplying the at least one rule to the input data, to determineanatomical identity of the first intrabody region, also while thecondition indicative of proximity remains satisfied, therebycharacterizing the position of the intrabody probe with respect to thefossa ovalis of the first intrabody region included in the interatrialseptum of the second intrabody region.